A compact wideband differential interconnect for complete series DC-isolation of integrated circuits above 100 GHz

A wideband interconnect with complete DC-isolation property (both in the Signal and Ground paths) for differential TEM transmission lines (like broadside-coupled striplines) is presented. The overall length of the proposed structure is only 0.1λg at the center frequency of 100 ∼ 500 GHz frequency band. The simulated interconnect shows more than 20 dB of return losses at the input and output ports in 130 ∼ 280 GHz band (about 0.7 octave). In addition, more than 15dB of return losses is achieved in the simulations in the entire 100 ∼ 500 GHz frequency band. The built-in DC-isolation property of both the Signal and Ground paths, makes the presented interconnect a suitable solution for Signal-Ground swapping applications of integrated active circuits, like that of the microstrip to inverted-microstrip transitions. The presented design procedure is applicable to various standard IC fabrication processes.